rhizome: an underground stem, usually horizontal and rooting at nodes.

right-of-way: a narrow corridor of land in straight sections across the landscape, repeatedly cleared and kept in low vegetation, to accommodate roadway structures, poles and wire for electrical and telephone transmissions, and pipelines.

riparian: situated or dwelling on the bank or floodplain of a river, stream, or other body of water.

root collar: the surface area of a perennial where the stem and roots join.

rootcrown: the part of a perennial plant where the stem and roots join, often swollen.

root sprout: a plant originating from a root or rhizome that takes root at nodes.

rootstock: the part of a perennial plant near the soil surface where roots and shoots originate.

rosette (basal rosette): a circular cluster of leaves on or near the soil surface radiating from a rootcrown, as in dandelions.

scaly: covered with minute flattened, platelike structures.

semievergreen: tardily deciduous or maintaining green foliage during winter only in sheltered locations.

semiwoody plants: species that have mostly woody stems and deciduous leaves, usually shorter than shrubs.

sepal: a single unit of the calyx; the lowermost whorl of flower parts.

serrate: margin with sharp forward-pointing teeth.

sessile: attached without a stalk, such as a leaf attached without a petiole.

shade intolerant: a plant that cannot grow and reproduce under the canopy of other plants but needs direct sunlight.

shade tolerant: a plant that can grow and reproduce under the canopy of other plants.

sheath: a more or less tubular portion of a structure surrounding another structure, such as the tubular portion of leaf bases of grasses that surround the stem.

shrub: a wood plant, typically multistemmed and shorter than a tree.

simple: not compound; single; undivided; unbranched.

smooth: not rough to the touch, usually hairless (or only finely hairy) and scaleless.

spherical: round in three dimensions, like a ball; synonymous with globose.

spike: an elongated, unbranched inflorescence with sessile or unstalked flowers along its length, the flowers generally maturing from the bottom upward.